Apparatus for rolling or drawing of tubes



June 5, 1934.

w. H. ENGELBERTZ APPARATUS FOR ROLLING 0R DRAWING 0F vTUBES Filed Dec. 8, 1935 Patented June 5, 1934 l 1,961,209 APPARATUS Fon noLLmG on naAwnvG or TUBES william n. Engelbermrittsburgh, Pa.

Application December 8, 1933, Serial No. 701,461

, Germany August 15, 1933 6 Claims.

The invention has reference to apparatus for the manufacture of seamless tubes or other tubular articles from cupped billets, that is, hollow bodies closed at one end. In the-push bench i apparatus such cupped billet is placed on the forward end of a mandrel and drawn into a tube by forcing it through a succession of ring-shaped dies with gradually decreasing diameter. Seamless tubes from cupped billets are also manu- 10 factured in rolling apparatus wherein mandrel and billet is held stationary while the rolling means move over it, or vice versa. Inboth of these methods of producing tubes from cupped billets over a mandrel, the used mandrel is re' turned to its initial position for further use after having been loosened and separated from the tube. Such mandrels cause much concern among tube manufacturers, especially those used in the push bench, wherein, as a result of having been forced through the dies with an extremely hot lbillet on its forward end, the mandrel shows an increase in diameter at that end. This, of course, results in the production of a tube of inferior quality and, besides that, the separation of such an out-of-size mandrel and the tube is a difficult task. Special equipment is used to reshape such mandrels. Another cause of concern is the high stresses arising within the mandrel during and after the tube forming operation, due to the tremendous axial thrust and the high temperature of the billet-carrying forward end of the mandrel which tend to deform the material-fibers beyond their limit of elasticity. Therefore, it has been recently suggested to place the used mandrels in a heating furnace which equalizes the mandrel temperature in order to relieve the fiber-stresses within the mandrel. Naturally, such mandrel-ills and their treatment will sub- Stantially increase the tube manufacturing costs.

'Ihe special object of this invention is to provide a' mandrel for tube rolling or drawing apparatus and a method of handling the mandrel therein so as to eliminate the disadvantages, referred to above, inthe manufacture of seamless tubes or other tubular articles from cupped billets. y

Another object of the invention is to provide a mandrel with two working ends so that either mandrel-end may receive and hold the heated "cup-Shaped billetwhile the same is formed into a tube on the mandrel. Thus, the life of the mandrel will be lengthened to twice that of the kind of mandrel used heretofore, and material 4stresses within the mandrel will be minimized.

A further object of the invention is to treat the mandrel after each use, that is, on its way back to the initial position for re-use, so as to equalize its temperature throughout and to rewstore the proper working temperature of the (c1. l aos-4) mandrel, without incurring additional expenses for equipment and time.

All advantages comprehended by this invention will be more fully demonstrated as the description progresses, and will be particularly pointed out in the appended claims.

Reference should be made to the accompanying drawing which Shows the preferred embodiment of the invention, in which-Fig. 1 is a plane view in Somewhat diagrammatical form, of one type of tube forming apparatus. Fig. 2 shows the new type of mandrel, suggested by the invention. Fig. 3 shows an old type of mandrel. Fig. 4' is an enlarged cross section taken on line X-X of Fig. 1, Fig. 5 is an enlarged side view of the mandrel holding means, constituting part of the tube-and-mandrel separating means.

The operation of the apparatus may be performed as follows: Referring tol Fig. 1, after billet 1 has been brought into alinement with dies 2, 3, 4, 5, and mandrel 6, said mandrel will be advanced in the direction of arrow A by the ram 7 connected to said mandrel by the medium of mandrel holder 8, thereby taking billet 1 upon its forward end and forcing it through said dies, whereby the billet is formed into a tube 9. Then, ram 'l and holder 8 is withdrawn while mandrel 6 and tube 9 proceed to a pair of cross rolls 10 or other suitable means which loosen the hold vof the tube on the mandrel. After leaving the last-mentioned means and advancing in the direction of arrow B, the tube has its forward motion brought to a temporary standstill by the shiftable stop 11, whereupon the mandrel is varrested by grippers 12 operatedby the cylinders 13 which hold the mandrel stationary by gripping its free rear end. Suitable means, not shown on the drawing, then advance the tube in the direction of arrow B, after the tube has been released by lowering of stop l1.

After completion of the stripping operation, mandrel 6 will be released by the grippers 12 and moved over skids 14 by levers 15 in the direction .of arrow C to the conveyor 16. Here, the mandrel, while on the way back to its initial position, proceeds in the direction of arrow D and may be turned by table 17, as indicated for example by arrow E, for` reasons to be explained hereafter. At the end of said conveyor 16, levers 18 lift the used mandrel onto a table 19 of suitable design, as shown for instance in Figs. l and 4, to equalize and gradually reduce the temperature and to, simultaneously, restore the required working temperature of the mandrel which advances in the direction of arrow F and, after having attained its proper working temperature, is lifted from said table by levers 20 which place the mandrel back into working position for the following daube forming operation.

The mandrel 6, after being freed fromthe tube4 9 formed thereon and on the way back to its initial position, may be turned by table 17 in order that its rear-end and front-end change their position so that either mandrel-end will be utilized to receive and hold billet 1 duringits transformation into a tube l9 over said mandrel. Or, if desired, table 17 may turn every second mandrel 6 after use. Making use of the latter arrangement, the used mandrels, passing table 19 l for the purpose of having their temperature tion.

equalized" and reduced, advance side by side, and while turning, in the direction of arrow F with the hot end of a mandrel between, and constantly in contact with, the cooler ends of the preceding and succeeding 'mandreL and vice versa, thus substantially speeding up and completing the mandrel temperature reduction and equalization process within a reasonable amount of time. In this arrangement, an odd number of mandrels may be employed in order to have both mandrel-ends receive and hold the hot billet 1 an equal number of times.

Fig. 3 showsthe old type of mandrel, lmarked 21', and a fragment of its holder 22, used here- 'tofore in apparatus for the manufacture of tubes from cupped billets. As a matter of fact, said mandrel end 23 only can be,` and is, used to receive and carry billet 1 to be stretched into a tube 9 on the mandrel. Naturally, said mandrelend, due to its repeated use is easily overheated and, consequently, will be upset,A that is, increased in diameter, by the. high axial thrust imposed upon it during the billet stretching opera- Moreover, the great difference in temperature between front-end 23 and rear-end 24 of mandrel 21, cau'se stresses of the materialfibers within the mandrel, which also weaken its stability.

Either end of the suggested mandrel 6 may, in accordance with the invention, be utilized to hold the extremely hot billet 1 during its stretching operation. The mandrel 6 will last twice as long as the hereto-used mandrel 21, and is cheaper than the latter due to its simplicity of design.

While the drawing shows mandrel 6 with semi-circular shaped ends, this shall not limit the invention since the mandrel-ends may have any suitable form so that either end may support the cup-shaped billet 1 while said billet is formed into a tube. Instead of using a solid mandrel 6, comprising one piece, a hollow one which may consist of a seamless alloy steel tube having both ends closed, as indicated by dot-and-dash lines in Fig. 2, may be employed according to the invention, thus saving energy in handling such mandrel in the apparatus described. The same holds true with respect to the mandrel holder 8, a fragment of which is shown, and whose hollow form is indicated by dot-and-dash lines in Fig. 2.

Having described herein one embodiment of my invention with reference to the accompanying drawing, it will be understood that I do not limit myself to the precise details illustrated in, and described with reference to, that drawing.

I claim:

1. A tube making apparatus, comprising a series of tube forming dies, a solid mandrel supporting a cupped billet on its forward end, a solid mandrel holder,` and a machine part advancing the mandrel and the mandrel holder and forcing said mandrel with billet through said dies in one stroke, whereby said billet is elongated and formed into a tube; the said mandrel having two, preferablyalternately used, working ends, thereby adapting either mandrel end to receive a cupped billet, and to push such billet through said dies in one straight forward pass, thus reducing the wall-thickness of, and transforming, the billet into a tube over the mandrel.

2. A tube makingl apparatus, comprising a series of tube forming dies, a hollow mandrel supporting a cupped billet on its forward end, a hollow mandrel holder, -and a. machine part advancing the mandrel and the mandrel holder and forcing said mandrel with billet through said dies in one stroke, whereby said billet is elongated 4and formed into a tube; the said mandrel having two, preferably closed and alternately used, working ends, thereby adapting/either mandrel end to receive a cupped billet, and to push such billet through said dies in one straight forward pass, thus reducing the wall-thickness of, and transforming, the billet into a tube vover the mandrel.

3. In a tube making apparatus according to claim 1, reciprocating means gripping the rear end of the mandrel after the hold of the tube formed on the mandrel has been loosened, and arresting the mandrel while the tube is stripped 01T said mandrel, a mandrel turning device effecting a turn of the mandrel so as to have the front end of said mandrel in the rear, and vice versa, while the mandrel is returning to its initial position and whenre-used for the tube forming operation.

4. The method of handling mandrels in rolling or drawing apparatus of the character described, which comprises forcing the mandrel, having two working ends, with a cupped billet at one end through a succession of tube forming dies, loosening the mandrel from the adhering tube after completion of the tube forming operation, separating the mandrel from the tube while holding the mandrel stationary and advancing the tube, turning the mandrel after being freed from the tube and on the way back to its working position, so as to have its used end in the rear, and its cooler end in front, when re-used for the following tube forming operation.

5. The step in the method of handling mandrels in rolling or drawing apparatus according to claim 3, which comprises changing the position of every second mandrel after being separated from the tube formed thereon, so as to have the used hot end occupy the place of the cooler end of said mandrel, and vice versa, when entering and while passing means which equalize and reduce the temperature of said mandrel, and when placed in proper working position, and while forcing the cupped billet through the tube forming dies.

6. The method of normalizing used tube rolling or drawing mandrels having two preferably alternately acting working ends, comprised of assembling a plurality of used mandrels in closedup formation while still in their irregularly heated condition, so as to have the hot end of a mandrel always between, and in contact with, the cooler end of the preceding and succeeding mandrel, and of moving all mandrels at a time, while turning them, towards their' initial position; thereby gradually equalizing the temperature of the mandrels so as to restore their proper working temperature and, simultaneously, freeing the mandrels from internal stresses before being reused.

' WILLIAM H. ENGELBERTZ. 

